Though some Goldfish breeds are delecate, Common goldfish are actually
very hardy which is why they make such good pets. They can survive in outdoor
ponds (even at tempratures which freeze the surface) and will eat almost
anything.

However goldfish are also far messier than tropical fish, and produce a
lot more waste. They only have an intestinal tract, without a stomach. So
they cant digest excess proteins, and instead excreet it back into the water.
This is a problem that needs to be addressed either with heavy filtering,
frequent water changes, or both. If this is not done, they will eventually
pollute their own water to the point where it is toxic, and they will die.

WATER QUALITY

In general, water should be clear. But it is not an absolute indicator
of how good the water is for your fish. Cloudy water can still be fine,
and crystal clear water can still be toxic.

Water Changes

Water changes are the process of removing water from the aquarium and replacing
it with fresh tap water. Always remember to dechlorinate water. Dechlorinator
(also commonly called "water conditioner") is cheap and is sold
at virtually all pet stores.

Most tap water is chlorinated, because the chlorine kills bacteria and
parasites. Some people believe you can dechlorinate water simply by letting
it sit for 48 hours and letting the Chlorine evaporate, but that is not
entirely true. Even after that process, there will still be chemicals remaining
in the water that do not evaporate and can damage your fish. Water conditioner
will completely nullify these chemicals in addition to the Chlorine.

Water changes are never bad for your fish. You can do them every day. But
with proper filtration (and assuming your tank isnt overpopulated), you
can reduce the frequency of water changes to once or twice a month. Changing
20% to 50% of the water volume is good. Changing more than 50% of the water
should be avoided unless absolutely necessary to avoid stressing the fish.

Changing the water will instantly oxygenate the tank and will instantly
remove pollutants such as ammonia. So in an emergency there is nothing that
will correct water chemistry problems faster than a water change.

Do not forget to use water conditioner on the new water (any water going
into your tank needs to be dechlorinated), and if you use aquarium salt,
that will need to be (proportionally) replenished as well. You should make
an effort to make sure the water is the same approximate temperature as
the water in your tank to avoid stressing the fish as well.

Temperature

People often assume that Goldfish thrive in cold water because they are
often referred to as Cold Water fish. It is true that they can tolerate
temperatures as low as 30F degrees. Common goldfish can even weather periods
where ponds are frozen over, so long as they have enough oxygen and food.
But warmer temperatures are healthier because warm water is less hospitable
to parasites and bacteria. The ideal temprature of the tank should be in
the 72F to 85F degree range, and they can tolerate temperatures to as high
as 90F. Common aquarium heaters sold for tropical fish tanks will work just
fine for Goldfish as well.

Warmer water holds less oxygen however, so fewer fish should be kept in
warm tanks (or additional effort taken to increase oxygen, such as surface
agitation or airstones). Temperatures above 90 degrees run the risk of overheating
and killing the fish, so if you live in a very warm area, you will need
to take care to cool down the aquarium.

Temperature changes should be gradual so as not to stress the fish. All
aquariums should have a thermometer so you can track the temperature. Most
pet stores sell adhesive strips that you can stick on the outside of the
tank that are very cheap (under $2) and unobtrusive.

New fish should be acclimated to the water temperature before putting them
into the tank. Float the bag on the surface of the water for 15 or 20 mintues
before putting them into the tank. Dumping a new fish into the tank will
stress it and increase the possibility of illness or death.

Keep in mind that a stable temperature will discourage breeding behavior.
So if you want to breed them, you need to mimic conditions in nature; starting
from a cold period and gradually warming. See the breeding section for more
information.

WHAT IS pH?

Ph measures how acidic your
water is. A pH of 7 is considered neutral and is ideal for goldfish. Above
7 is considered alkaline (aka "Hard Water"). Below 7 is considered
acidic (aka "Soft Water").

The pH scale is logarithmic...so a pH of 5.5 is ten times as acidic as
a pH of 6.5. This is important in that the more radically the pH changes,
the more it will stress your fish. If the pH changes by more than 0.3 per
day, it will stress your fish. The "normal" range for most fish
is between 6.5 and 7.5.

Water can be "Hardened" (made more alkaline) or "Softend"
(made more acidic) by way of chemicals that you can buy at most pet stores.
Read the instructions and be very careful when altering your water pH. Carbon
Dioxied and high water temperatures will tend to make water more acidic
(lower the pH). Oxygenated water will tend to be higher pH.

Be aware that the importance of pH is often exaggerated. A stable pH is
more important than maintaining it in the ideal range for Goldfish. The
process of altering the pH of your tank is likely to stress the fish more
than the fact that it is not in the ideal range. The general consensus seems
to be that altering the pH of your water is more toruble than it is worth.
So you should only alter the pH if it is absolutely necessary.

AQUARIUM SALT

Aquarium Salt comes in
cartons like this

In nature, Freshwater is not the same as what comes out of your tap. Tap
water is truely salt free, but most freshwater is not. So a "freshwater"
aquarium can contain small amounts of salt and still be considered fresh water.
For this reason, many supposed "freshwater" fish will still tolerate
moderate amounts of salt in the water, and some even require it.

Goldfish dont absolutely require salt in their water, but it does enhance
their immune systems by stimulating them to produce more mucus over their
scales (often referred to as their "slime coat"). Goldfish are
supposed to be slimy. This is normal and desirable. Salt will enhance gill
function as well (allowing fish to absorb oxygen a little better) and reduces
the rate of nitrite buildup in the tank.

In addition, salt is toxic to many parasites that infect goldfish (including
Ick, the most common parasite). So a salt environment will augment their
immune systems in this way as well. Higher concentrations of salt are used
as "salt baths" to immerse sick fish in for short periods.

Salt Tolerance of Other Fish

Goldfish can tolerate low levels of salt. Almost all freshwater fish can
tolerate salt to some degree. But be aware that some freshwater fish do
not tolerate salt well at all, so make sure you dont have any of these fish
in your tank and do not plan on adding them. They include tetras, catfish
(including plecos/suckerfish), loaches, and any scaleless freshwater fish
(though the consensus seems to be that you shouldnt mix goldfish with tropical
fish anyway, salt or no salt). Snails are also not crazy about salt water,
but some freshwater snails can endure the amounts you will use in a goldfish
tank.

Be Sure to Use Only Aquarium
Salt

Do not use regular table salt. Table salt has Iodine, which is poisonous
to fish. You can use Kosher salt but its best to remove all doubt and just
use Aquarium Salt from a pet store that is specifically marketed for pet
freshwater fish. "Aquarium Salt" is not the same product as "Marine
Salt", which has additional stuff in it like calcium that marine fish
require. The extra stuff in the Marine Salt may alter you water chemistry
in ways you dont want. Marine salt is used for Salt water aquariums. Aquarium
salt is used for freshwater aquariums.

Always fully dissolve salt before adding it to the tank. Undissolved salt
can chemically burn your fish. Hot water will dissolve salt more rapidly,
as will agitation.

The normal amount of salt for a freshwater aquarium is one rounded tablespoon
per five gallons of water volume (there are three teaspoons in a tablespoon,
and two tablespoons equals one ounce). But follow the directions on the
box. To avoid stressing your fish, add the recommended amount of salt slowly
(1/4 normal amount per day for four days).

A low concentration of salt is 0.1% (1 teaspoon per gallon). A medium concentration
is between 0.1% and 0.5% (5 teaspoons per gallon). A high concentration
is 0.9% (9 teaspoons per gallon) or above.

High concentrations should only be used for very short term treatment for
sickness. Medium concentrations are dangerous in the long term and could
kill your live plants as well. 0.3% (one tablespoon per gallon) is the maximum
amount of salt that is safe for goldfish in the long term.

Keep Track of the Salt in Your
Tank

You must keep track of how much salt is in your aquarium. The only way
to remove salt is through water changes. Salt should be fully dissovled
before being added to the tank. If you lose track of how much salt is in
your aquarium, begin doing a series of 50% water changes (once a day) for
at least three days (a week is better). Then begin introducing salt again
as if it were fresh water.

Regarding Evaporation

To avoid accidentally putting too much salt in your aquarium, make sure
you top off the water in your tank BEFORE you do water changes.
Adding water does not remove salt from the tank, it only dilutes it. If
the water level is consistend whenever you remove water from the aquarium,
then you never have to worry about accidentally adding too much salt.

Replace salt in the new water (proportionally) before putting it into the
tank. Once the fish are already acclimated to salt water, you dont have
to worry about putting it in slowly anymore.

THE BIOLOGICAL FILTER

This chart illustrates how waste is processed by your biological figure. Click on the image to view a larger version.

This referrs to the bacteria that naturally live in your aquarium. You
dont have to put these in; they come in your fish and populate your tank
by themselves. They exist pretty much everywhere in nature except in your
tap water (because it is chlorinated).

The function of these bacteria in your aquarium is to neutralize waste
products in the water produced by the fish, thereby reducing the overall
frequency of water changes. Your biological filter will not remove the need
for water changes completely, it will just reduce how often you need to
do them.

Nitrification
(Aka "Biological Cycle", "Start up cycle", "Nitrogen
Cycle", or "Cycling") is the process by which beneficial
colonies of bacteria establish themselves in a new tank. They come with
your fish (so the process cannot start until you actually put fish in the
tank), but it takes a period of time before they can replicate themselves
sufficiently to function as a filter. You'll never actually see them...they
are very small. But they are there.

It is possible to cycle a tank without using any fish (by way of adding
ammonia yourself) but the process is involved and complicated. Pet stores
sell what amounts to fully cycled water in order to "jump start"
the process. But the best method is probably to use living fish and plants.

Be aware that Chlorine will kill these bacteria. So if you
are washing places where they live (filter pads, gravel, ect...) you need
to make sure that the water you use is already dechlorinated. These bacteria
live everywhere in your aquarium, but the biggest concentrations will be
where there is moving water. Like your filter (and any media in your filter)
or the gravel (if you have an undergravel filter). Most power filters contain
filter media with the sole purpose of providing a home for these bacteria,
so that you will not lose your biological filter when you
change filter pads.

Do not be fooled by crystal clear water; the fact that your tank looks
clean does not mean it is not toxic to the fish. Unlike a lake or a river,
an aquarium is a closed system. Waste products produced by your fish and
from decaying food in the tank remain in the tank unless they are removed
or neutralized.

This can be accomplished by frequent (daily) water changes, but for most
people this is impractical. The alternative is a biological filter; using
plants or colonies of benign bacteria to convert the waste for you, so you
dont have to change the water as often.

Ammonia

When urine and feces decompose in the tank, ammonia is released. There
are two types of ammonia, but only one is dangerous to fish. When talking
about ammonia levels, this is the type of ammonia that is a concern. Any
amount above 0ppm (zero parts per million) is toxic, but levels at 2ppm
or more is dangerous. Ammonia levels typically begin rising the 3rd day
after fish are introduced to the tank.

An Ammonia Test Kit

If you want to remove all doubt, you can buy a monitor strip from any pet
store. These look similar to thermometors that suction-cup to the inside
of your tank. They provide a real-time measure of how much ammonia is in
the water at any given time. They work continuously, but need to be replaced
every one or two months. They typically cost between $6 and $10 if you buy
them individually. Pet stores also sell kits with replacement strips that
will average out much cheaper.

Nitrosomas

These are the first type of bacteria that live in the tank. They eat ammonia,
but excrete Nitrites,
which are also toxic to fish. Nitrite levels begin rising the first week
after fish are introduced.

Nitrobacter

This is the second type of bacteria that live in your tank. They eat Nitrites
and spit out Nitrates. Nitrates
are also toxic to fish but to a lesser degree, and are harmless at low or
moderate levels.

So the point of the biological filter is to convert substances which are
very toxic to your fish into substances which are only mildly toxic. Water
changes still need to be done to remove nitrates once they get too high,
but because your fish have a much higher tolerance for them, water changes
can be farther between. Live plants can further augment your biological
filter, but have potential problems of their own (see the plant section
Setup and Maintanence for more info)

Kits to test for these chemicals are available at any pet store. The cycle
is fully established between 2 and 6 weeks after the fish are first intruduced.
The bacteria grow more slowly in cold water. So warmer water will accelerate
the cycle.

A Note on Changing Your Filter Media

The filter media in your power filter (if you have one) is where most of
the bacteria live. When you throw this away, you killing off the bacteria,
and they have to start over with the new media. When changing your filter
media, keep in mind that your biological filter will be weakened until it
can re-establish itself. For this reason, many commercial filters use separate
media...one on which the bacteria grow (which is never changed) and one
which is disposable and can be periodically replaced.

ABOUT SNAILS

There are many species of undesirable pond snails that infest aquariums

Aside from their asthetic value, snails eat one of the true pests of an
aquarium; algea.

That being said, moderate to high levels of algea will still
reproduce faster than the snails can eat them, and you will still need to
scape them off occasionally. Snails dont eat algea evenly either,
so are only really effective at controlling low levels of algea.
They do eat live plants as well, but not to
a great degree. Any live plants that can withstand the constant pecking
of goldfish will probably endure snails as well.

Most freshwater aquarium snails are from the species Marisa
Cornuarietis (part of the family Ampullariidae...aka "Apple Snails").
Like goldfish, these have been bred into a variety of shapes and colors,
but they are all the same species. Marisa Cornuarietis are not asexual,
unlike some snails. So if you want them to reproduce,
you'll need at least two.

An Apple snail

Their reproductive process involves laying a clutch of eggs outside the
water (so they will need several inches of space above the water line).
Their eggs vary from pale to bright orange and look vaguely like a teaspoon
full of tapioca pudding clinging to the glass. They gestate in about a month.
The eggs need to stay moist but cannot be submerged, or the young will drown.

The other type of snail common to freshwater aquariums is the pond snail.
This is a generic term that covers several species of snails that are considered
pests. These are asexual, and a single one of them can quickly pollute your
tank with dozens more just like it in a very short time.

They are generally undesirable because they are so small; they are not
asthetically pleasing and dont eat algea very well. They tend not to last
long in goldfish tanks though, because goldfish will eagarly eat them. For
this reason, a lot of petstores will put a goldfish in with their tropical
fish to eat any pond snails that are in the tank.

A Black Mystery Snail, a type of Apple Snail

Other snails should get along with most goldfish fine, although the goldfish
may nip at them. For this reason you should keep snails that are big enough
that they can weather this behavior (if they are about the size of the largest
fish's head or larger, they should do fine). Most goldfish will ignore snails
that are too large for them to swallow whole.

Where water conditions are concerned, they should be able to survive in
any environment that goldfish can survive in. The general consensus seems
to be that aquarium salt is bad for snails, but they can endure the low
concentrations found in freshwater tanks. There is a website called Applesnail.Net
that has more in-depth information about Apple Snails.

GOLDFISH FEEDING

Goldfish are omnivores, and will eat anything they can fit into their mouths.
They originated as bottom feeders (similar to catfish) and prefer foods
that sink to the bottom or float in the middle, but can eat common flake
food on a daily basis. The only reason floating foods arent great for them
is because it forces them to swallow air while feeding.

What To Feed Them

As a staple food, the best food you can feed them is pellets. Most chain
stores will sell pellet food of some kind. Pellet food is more nutritious
than flake food, and does not easily decompose the way flake food does (so
uneaten pellets wont pollute your tank). It will also enhance the color
of your goldfish as well. Hikari is one of the major manufacturers of Goldfish-specific
pellet food, but Koi pellet food will work just as well. just make sure
the pellets are small enough that your goldfish can swallow them.

An example of Goldfish pellet food

Most owners also feed them live (or freeze dried) food such as blood worms
or brine shrimp once a week as a supplement. These are very good for the
fish because they are high in protien, but will cause digestive problems
if given every day. Goldfish will be very happy to eat the live versions
of these foods, but freeze dried versions remove the possibility of parasites
infesting it. Live food sold at most pet stores is unlikely to have parasites,
but with freeze dried foods the chances are almost zero.

The amount of protein they consume (including blood worms, brine shrimp,
ect..) should be limited when possible. High protein foods stress their
digestive systems. You can be more liberal feeding them fruits and vegetables.
Since they contain less protein, they wont stress the fishs' digestive systems
as much.

Yes, Goldfish can eat raw fruits and vegetables, and such food is actually
good for them. The food should be cut small enough that they can eat it,
though they can tear off pieces of more supple foods (like oranges). A lot
of people put cut slices in the tank. The fish will graze on it like cattle.
Typical foods include oranges (the vitamin C boosts their immune system),
skinless peas (often used to treat digestive problems), and lettuce. Cut
it in sections that are small enough that they can either swallow it whole
or bite off chunks of it. Oranges (or other fruits containing citiric acid)
should not significantly alter the water chemistry, but excess food should
be removed from the tank once they are done feeding.

How Often to Feed Them

Feed them as much as they can consume in a 5 minute period, and only feed
them twice a day max. People often overestimate how much food to feed goldfish.
You have to remember that goldfish are cold blooded, and are kept in an
environment where they dont have to expend a lot of energy looking for food
or avoiding predators. Feeding them once a day is plenty, and they will
actually do fine being fed only a few times a week.

With fruits and vegtables, you can be a bit more liberal. These foods are
not dense protein sources, and so are much easier on their digestive systems.

Avoid Overfeeding

One reason people feed their goldfish so much is because they believe the
fish are hungry. But goldfish are ALWAYS hungry. Goldfish are gluttons...they
will literally eat until they explode. They are biologically programmed
to eat continuously. In the wild, this is a good thing. In captivity, it
is dangerous for them. At best, overfeeding them will result in lots of
fecal matter which will decay quickly and pollute your aquarium with ammonia.
At worst, overfeeding will eventually cause their intestinal tracts to rupture
and they will die. So you have to be careful in how much they are fed, especially
for smaller fish.

Keep the high-protein foods (like blood worms and shrimp) as a once or
twice a week treat to augment their normal diet of flakes or pellets. Feed
only once a day or every other day. A sign of overfeeding is a line of feces
trailing from their cloaca. If you see this, you need to reduce the amount
of food you are giving them. It is always better to underfeed than to overfeed.

Sickness
Links:

Animal
World - Comprehensive list of diseases, symptoms, and their treatments.

Sickness is most often caused by stress. All fish endures a low level of
infection constantly. This is natural and normal. Their immune systems can
keep it in check so long as they are healthy. When you handle the fish,
or when they are scared, it will cause stress. This will weaken their immune
system, which will allow the infections they already have to become stronger.
Other factors are parasites and bacteria that are introduced through new
fish or live food, injuries, and dirty or contaminated water.

The links to the right have more detailed information on specific illnesses,
In this section I will simply give a brief summary of the most common ones.

Preventing Sickness

Maintaining good water quality is the best method of prevention, and the
best way to help the fish's immune system recover. Adding aquarium salt
to the tank will enhance their mucus layer and improve the function of their
immune system. Salt is also toxic to most parasites as well.

Do NOT pet your goldfish. Many goldfish can become very tame, and some
even seem to crave this kind of attention. But petting them rubs off the
mucus layer (sometimes called the "Slime Coat") that covers their
scales and protects them from parasites and bacteria. Fish are not puppies.
Handle them only when absolutely necessary.

Treatment of Sicknesses

Most diseases can be cured using broad-spectrum anti-biotics from a pet
store in conjunction with salt. "Broad Spectrum" means it is basically
lots of medications rolled into one...a sort of shotgun solution that spams
a bunch of medications at the disease in the hope that one of them will
work. And this method often works. Follow the instructions carefully though.

Salt Dips and Baths

Salt is bad for virtually all aquarium parasites and bacteria. So a common
solution to sickness is to submerge the fish in higher than normal concentrations
of salt in an effort to kill off large portions of the disease and give
the fish's imune system a running start. Salt baths and dips should only
use Aquarium salt. Not Table salt or Marine salt.

You do not need an aquarium for a salt bath...just a container large enough
for the fish to swim in for the duration of the treatment. Once you have
a container, fill it with fresh dechlorinated water that is within 3 degrees
(F) of the temperature of the tank you removed the fish from, and add the
amounts of salt (fully dissolved) listed below. The salt should not be dangerous
to the fish so long as you do not exceed the treatment times. But it is
uncomfortable for the fish, so minor agitation is normal. Small or weakened
fish should not be subjected to a Dip, only a Bath.

A SaltBath is the normal
course of treatment. Add 1 tablespoon of salt per gallon of water volume.
Treatment should take be between 30 minutes to one hour.

A SaltDip is a more extreme
course of treatment, and is more stressful to the fish. Add 1/2 cup of salt
per gallon of water volume. Submerge the fish for at least 30 seconds but
no longer than five minutes.

Remember to remove carbon filters when medicating, as they will filter
the medication from the water. What follows is a list of the most common
types of Goldfish illnesses and brief instructions on how to treat them.

This Chocolate Oranda is infected with Ick

Ick (Ichthyophthirius multifiliis)

Probably the single most common disease in the aquarium hobby, Ick
is a parasite that looks like tiny white dots on the surface of the fish.
It is potentially fatal if left unchecked, but easy to treat. Ick-specific
medication is sold at any pet store and is cheap. Ick does not tolerate
salt well at all, and adding aquarium salt to your tank will prevent ick
infections and help to accelerate the recovery of fish that are already
infected. When treated properly, ick can be cured in as little as 2 or 3
days. It is a virtual certainty that you will come across this disease eventually,
no matter how clean your aquarium is, so you should always keep some ick
treatment on hand just in case.

No, this fish isnt dead. It just cant stay upright because it's swim bladder is not functioning properly.

Swim Bladder Disorder

Fish maintain their balance in the water by use of an organ called the
swim bladder. If
it is deformed or diseased, they will be unable to regulate it and keep
their balance. Symptoms include the fish being unable to stay upright and
level in the water. The fish may sink to the bottom of the tank or be stuck
at the surface. It may even float upside down. The fish will become listless
and will probably stop eating, but will otherwise be alert.

Many exotic goldfish suffer from this to some degree due to their body
shapes. Countless generations of inbreeding have deformed many of their
internal organs, and the swim bladder is no exception. If it is due to a
genetic deformity of the organ, there is probably not a lot you can do.
But if the fish was swimming normally before, and these symptoms appear
in the space of a few days, it is probably due to disease or a dietary problem
(like constipation), and not a genetic flaw.

The dietary problem is easy to fix; stop feeding the fish for a few days.
Then feed it steamed, de-skinned, and crushed peas (which will cure constipation)
until it starts swimming normally again. If it is due to disease, you will
need to cure the underlying infection. If you do not know what the infection
is, try a broad-spectrum antibiotic.

High nitrate levels can cause swim bladder disorder as well, so be sure
to test for Nitrates to make sure swim bladder disorder isnt simply a symptom
of Nitrate poisoning.

Fin rot is easy to spot from the frayed edges of your fish's fins

If the problem is due to diet or disease, it could become serious enough
to kill the fish. If it is due to a genetic flaw, it is likely the fish
will live just fine (though it will probably be irritated at not being able
to move around), assuming it can eat.

Fin Rot

Probably the result of bacterial or fungal infection due to stress, but
it can also mean the water has a PH that is too high. Symptoms are ragged
or frayed fins. Fin
Rot starts at the outer edges and eats it's way to the base. If treated,
the fish will eventually recover fully and the fin will re-grow normally.
If it reaches the base of the fin however, the fish will never be able to
re-grow the fin again. So while it probably wont be fatal, you still need
to treat it as soon as possible.

If the fin rot is due to pH, you will need to fix your aquarium pH to stop
the fin rot. If it is due to an infection, you simply treat it with medication.
There are fin rot-specific medications you can buy at the pet store, but
broad spectrum antibiotics will usually medicate fin rot infections as well.
Fin Rot may require multiple cycles of treatment to erradicate completely.

An extreme example of Dropsy. Most fish will exhibit more mild symptoms, but the result is the same.

Dropsy

Dropsy itself is not a disease, but a symptom. Usually caused by a bacterial
infection of the Kidney, the fish's body will bloat due to fluid build-up
in it's organs and it's scales will stand out like a pinecone.

There are dropsy-specific medications available from many pet stores. Epsom
Salts will also help by leeching fluid out of the fish (use a small
amount...1/8 teaspoon per 5 gallons or 20mg per liter). Use this IN PLACE
of Aquarium salt, not in addition to aquarium salt.

The consensus seems to be that Dropsy is 95% fatal however. The organs
are destroyed, and even though the fish may appear to get better for a week
or two, eventually the organ failure will kill it. Even if the fish survives,
it will likely suffer permanent damage from the disease.

Unlike Ick, Dropsy
is not very contagious. But the infected fish should be removed from the
tank as soon as possible. Medication for Dropsy can be bought from any Aquarium
specialty store. If the fish survives at all, it should recover with a week.

Oxygen Deprivation

If the oxygen content in the water is too low, the goldfish will become
lethargic (sitting at the bottom of the tank and not moving around), and
attempt to gulp air from the surface (a behavior commonly known as "piping").
Eventually the fish will suffocate and die.

Warm water has lower oxygen content than cooler water, so the warmer the
water the more you have to pay attention. Surface agitation (bubbles) will
encourage gas exchange and put more oxygen into the water. Power heads,
airstones, and bubble walls will also oxygenate the water very well for
the same reason.

An immediate solution to oxygen depravation is a simple water change. Thats
it. Changing the water will instantly give the fish oxygen. But if it is
a continual problem, it may mean you need a bigger tank (more surface area
for gas exchange) or fewer fish.

Velvet

Velvet appears similar to ick, but the spots are much smaller and have
a yellow color to them (which is why it is sometimes also called "Gold
Dust Disease"). Like Ick, Velvet is also a parasite, and is usually
caused by damage to the Goldfish's slime coat. Symptoms can include "flashing"...where
the fish rubs up against objects or gravel. Velvet is more contageous than
Ick, and more likely to kill the fish than Ick.

Most pet stores sell borad spectrum antibiotics that include medication
for Velvet, but medications that cure Ick may work against Velvet as well.
Velvet can spread quickly, so the fish should be medicated as soon as symptoms
are discovered.